Printing telegraph



Aug. 18,1925. 1,549,820 G. S. VER NAM Y PRINTING TELEGRAPH Filed ,Jan; 12. 1922 2 snees-snee 1 I /m/e/770r I "G/Xeff 5T Var/7am Patented Aug. 18, 1925.

UNETE STATES EA'K'EN'E GILBERT S. VERNAM, 0F BRO'OKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

PRINTING TELEGRAPH.

Application filed January 12, 1922.

To all whom it may concern:

Be it known that I, GILBERT S. VERNAM, residing at Brooklyn, in the county of Kings and State of New York, have in- 5 vented certain Improvements in Printing T elegraphs, specification.

of which the following is a This invention relates to telegraph sys tems.

An object of the invention is to provide a system whereby a plurality of telegraph messages originating at separate stations may be transmitted over a plurality of brancl'i lines or extension circuits to main or central stations, where synchronous multiplex apparatus is located for automatically and simultaneously transferring the code combinations of message impulses to a line connecting the central stations.

Another object is the provision of means associated with the synchronous multiplex apparatus at the central stations for providing a? complete overlap between the selections received from the extension circuits or branch lines and those. transmitted by the synchronous multiplex apparatus to the line cei red from the start-stop apparatus and those transmitted by the synchronous'multiplex apparatus so that irrespective of what the phase relation between the start-stop and the synchronous multiplex apparatus is, the selections coming in on the start-stop apparatus will be correctly transmitted to the multiplex apparatus provided that the speed of the start-stop apparatus is equal to or slightly less than the speed of the multiplex apparatus.

Likewise accordin to one of Serial No. 528,763.

the embodiments of the invention there is provided intermediate the multiplex apparatus associated with the line conductor connecting the two stations and the start-stop apparatus which transmits the impulses re ceived from the synchronous multiplex ap paratus to the extension circuits, means such as a group of relays operative in conjunction with a second group oi relays for providing an overlap between the selections received on the multiplex apparatus and those transmitted by the start-stop apparatus.

The invention is illustrated in the accompanying drawings which represents one embodin'ient of the invention and when arranged so that Figure l is to the left of Fig. 2 a complete system is shown diagrammatically.

The invention, in the embodiment disclosed comprises a branch oflice A which is connected with a main or central ofiice B by an extension circuit or branch line 6, a central or main station C connected with the main station B by a line 7 equipped with duplex apparatus and a distant branch o'flice D which like branch ohice A is connected with the associated central station C by an extension circuit 8.

At the branch office A there are located transmitting and receiving equipments E and F respectively, being shown diagrammatically. The extension circuit 6 may be a pair of line conductors or a single line conductor equipped with duplex apparatus, as illustrated in the drawings. Both the central stations B and C are provided with receiving distributors G and H of the startstop type to receive the code combinations of message impulses from the respective substations or the branch offices and transfer them to the multiplex synchronous distributors I and L also located at the otiices B and C respectively through the instrumentalities of a series of condensers and storing relays. Also located at the central ori ices are the synchronous multiplex distributors K and M each of which serve to receive the signaling impulses from the line conductor 7 connecting these two stations and transfer the same to the start-stop disributors N and B respectively through the instrumentalities of a single group of relays operative in conjunction with a series of loop control relays, which according to the present invention provide an overlap between the selections received on the synchronous multiplex distributor and those transmitted to the extension circuits by the start-stop distributors associated therewith. Branch otlice D like branch oiiice A is provided with a transmitting distributor P and a receiving d1stributor Q, which serve their respective purposes. F or the sake of clarifving and simplifying the drawing b the apparatus com mon to one channel has been shown in detail, while that individual to the other channel has been shown schematically.

The transmitting equipment E comprises an intermittently rotary distributor 1O having a brush arm 11 which carries a pair of brushes 12 and 13, which in turn are arranged to make contact with rings 14, 15, 16 and 17. The outer ring 17 is divided into a plurality of segments 18, 19, 20, 21, 22 and 23, which are connected with the respective contacts of a transmitter shown diagrammatically at 2 1. In order that the brush arm 11 will be stopped and released once per revolution, a release magnet 27 is provided which is under the control of a start relay 28 being controlled by a common contact associated with the transmitter 24 The transmitter 24 consists of a plurality of movable contacts 30, 31, 32, 33 and 3% which are connected to the respective segments forming the outer ring 17 of the distributor 10. Also associated with the transmitter 2 1 is a common contact 35 which previously stated controls the energization of the start relay 28. Although the transmitter 2 1 has been shown diagrammatically as a keyboard transmitter, any well-known type of transmitter may be substituted therefor which will provide equally good results.

At the central oflice B there is shown a receiving distributor G of the start-stop type and a synchronously operated distributor I which has its continuous ring 95 connected to the apex of the ratio arms which includes the receiving relay 99 forming a part of the duplex equipment associated with the line conductor 7. The line relay 99 responds only to incoming impulses and is non-responsive to outgoing impulses. Upon the operation of the multiplex distributor I, this relay will not respond to impulses which may be transferred thereto from the start-stop distributor G.

The start-stop distributor G comprises an outer ring 44: and an inner ring 40. Fornr ing a part of the outer ring is a plurality of segments 47, 4-8, 19, 50, 51, 52 and 53, the first five of which correspond to respective ones of the segments on the transmitting distributor 10. By the proper orientation of these segments and inasmuch as they are smaller than the transmitting segments of the transmitting distributor 10, the central portion of the signal impulse transmitted over the extension circuit 6 to the line relay 37, will be picked up for each segment of the sending face at the branch ofiice A. The distributor G also comprises a brush arm 11 carrying brush 42 which is held against rotation by a release latch under the control of release magnet 39.

Interposed between the start-stop distributor G and the multiplex or synchro nously operated distributor I is a set or condensers in combination with a single group of storing relays operable in accord ance with the signals transmitted and controlled by a series of transfer relays under the control of both the start-stop distributor G and the multiplex distributor I. The set of condensers and the single group of storing relays serve to provide a complete overlap between the selections received from the startstop distributor G and those transmitted over the line 7 by the multiplex distributor I irrespective of what the phase relation is between the brush arm of the startstop distributor G and the brush arm of the multiplex distributor I providing, of course, that the mean speed of the brush arm of the start-stop distributor is equal to or slightly less than that of the brush arm of the multiplex distributor I. The condensers 56, 57, 58, 59, and 60 are connected directly to the receiving segments forming the outer ring of the distributor G and will be charged in accordance with the ope-ration of relay 38. During certain periods of operation however, the impulses received on the segments 47 to 51 inclusive will be transferred directly through the armatures and contacts of the transfer relays 70, 71 and 7 2 to the right-hand windings of the set of storing relays 7 6 to inclusive as will be more clearly described hereinafter. The energization of the transfer relays 70, 71 and 72 is controlled jointly by the start-stop distributor G and the multiplex distributor I, so that no mutilation or piling up of the signaling impulses will result should one distributor be out of phase with respect to the other. Upon the energization of the storing relays 76 to 80 inclusive, a locking circuit is established therefor which is un der the control of the multiplex distributor I and which will be released once per revolution thereof. After a set of impulses have been transmitted from the distributor G to the condensers 56 to 60 and upon the re lease of the transfer relays 70, 71 and 72. a discharge circuit is established for these condensers extending through the right hand winding of the corresponding ones of the storing relays 7 6 to 80 which thereupon attract their armatures and establish a lock ing circuit therefor. These relays will be locked up through their own contacts and left hand windings, thus after their initial energization are maintained energized independent of the condensers 56 to 60. It is through the contacts of the relays 76 to 80 that the polarity of the impulses corresponding to the various characters is varied.

In order that the impulses may be transferred from the respective parts of the circuit so that no mutilation of signals will result such transfer is under the joint control of the start-stop distributor G and the synchronous multiplex distributor I as will be more clearly described hereinafter.

The apparatus just described constitutes the equipment located at the central or main station B and which serves to transmit impulses from the branch oiiice A to the line conductor 7 and thence to the central oilice C from whence the message impulses are transmitted to the distant branch oitice D.

The apparatus at the central o'liice C which receives the signals transmitted from the transmitting apparatus located at the central ofiice B, comprises a multiplex distributor M and a distributor of the startstop type R. The multiplex distributor M comprises among other parts a continuous ring 113 and an outer ring which is divided into a plurality of segments such as 107, 108, 109, and 111. Like the distributor I a continuously revolving brush arm 102 carrying brushes 103 and 104 is also provided. Connected to the smaller segments,

forming a part of the outer ring are the windings of a set of storing relays 115, 116, 111. 118 and 119 which in combination with a group of loop control relays 122 to 126 inclusive provide an overlap between the selections received on the multiplex distributor M and those transmitted over the extension circuit 8 by the start-stop distributor R.

The start-stop distributor R comprises an outer ring divided into a plurality of smaller segments 132, 133, 13 1, 185, 186 and 137, the first five of these segments are connected to the windings of the loop control relays to 126, which are energized upon the passage of the brush 130 over the segments individual thereto, depending upon whether the relays 115 to 119 inclusive are at this time energized. The loop control relays will remain energized until the brush 130 has passed off of the segment to which they are connected due to the establishment of locking circuit therefor through their can contacts. For bridging the outer ring of the distributor R with the inner ring 138 the distributor R has a brush 130 carried by a brush arm 128 which is normally held against rotation by a release latch under the control of a release magnet 131. The release magnet 131 is controlled through the contacts of a control relay 127, the energizing circuit of which is complete upon the energization of any one of the relays 115 to 119 inclusive.

The receiving equipment Q at the branch oiiice D comprises a receiving printerdiagrammatically shown at which comprises the usual selecting magnets 156 to 160 inclusive and the printing magnet 168, the respective magnets have their windings connected to segments 161, 162, 163, 164 and 165 forming a part of the outer ring of the receiving distributor. This distributor L like the distributor G, has a brush arm 1&7 carrying a brush 148 which is arranged to bridge the segments forming a part of the outer ring with the segments 151, 162 and 152 for controlling the energization of the respective ones of the selecting magnets depending upon the energization of relay 151, which in turn is controlled by the line relay 146 connected to the extension circuit 8.

Inasmuch as the apparatus associated with the other channel of the system is identical with the equipment just described further description thereof is considered unnecessary here. The rectangles designated by the characters S and T represent the equipment intermediate the distributors G and I and H and B respectively which as previously described are shown diagrammatically for the sake of clarifying the drawings.

The operation of the equipment just described is as tollows: Assume for the sake of clearness that the branch oiiice A desires to communicate with the branch ofiice D, in which case the transmitter 2 1 will be operated to set up a particular combination depending upon the message desired to be transmitted. Let it also be assumed that it is desired to transmit a character in which contacts 30, 32 and 31 of the transmitter 24: are actuated for closing their respective contacts.

As previously described, upon the operation of the transmitter 24, contact 35 will be closed for causing the energization of the start relay 28, the energizing circuit oi which extends from battery through the left hand winding thereof, contact 35, segment 15, brush 13 and the segment 14; of the transmitting distributor 10 to ground. The start relay 28 is thereupon energized and is locked up over a circuit under the control of brush 18. Upon the energization of start relay 28 an energizing circuit is established for release magnet 27 which in operating withdraws the release latch under its control from engagement with the brush arm 11, which is thereupon tree to rotate whereupon the brush 12 consecutively completes circuit extending from the segments 18, 19, 20, 21 and 22 and the contacts of the transmitter 2 1 which have been ion ' operated through the winding of the pole changing relay 29. The pole changing relay 29 is energized upon the passage of the brush 12 over the segment to which one of the closed contacts of the transmitter 24 is connected for applying to the line 6 an impulse of a polarity corresponding to that normally applied thereto. The instant the brush 12 passes off of segment 23 an open circuit condition is established whereby the pole changing relay 29 reverses the position of its armature and connects the positive source of current with the apex of the ratio arms to which the receiving relay 36 is connected, but which does not respond to outgoing impulses. Relay 37 located at the central office B does however, respond to such change in polarity and reverses the position of its armature whereby the energizing circuit of relay 38 is broken, consequently an energizing circuit for the release magnet 39 of the distributor G- is established extending from battery through the winding of release magnet 39, segment 53, brush 42, segment 54 of the distributor G and the winding of relay 61 to ground. Relay 61 in attracting its armature causes a momentary charging of the condenser 67 which is normally short-circuited by the high resistance 68, through the left hand winding of relay 62. Relay 62 thereupon attracts its armatures which conditions an energizing circuit for relay 63 but which is not completed until the bridging of the segments 52 and 46 by the brush 42. At the right hand armature and contact of this relay, an e11- ergizing circuit is established for the transfer relays 70, 71 and 72 extending from battery through the right hand winding of relay 62, windings of relays 72, 71 and 7 O in series and the right hand armature and contact of relay 66 to ground. Relay 62 is locked up over the circuit just traced and is maintained energized until the energization of relay 66 and the subsequent release of relay as will be described later.

The release magnet 39 being energized, the brush arm 41 is thereby released for rotation. Owing to the withdrawal of the release latch under its control and contact 30 of the transmitter 24 being closed an energizing circuit for the pole changing relay 29 is established upon the passage of the brush 12 over the segment 18 of the transmitting distributor 10, thus connecting the negative pole of the battery with the line conductor 6 and consequently causing the reversal of the armature of receiving relay 37 to the position shown in the drawing which in turn causes the energization of relay 38. The closure of the front contact of relay 38 establishes upon the passage of the brush 42 over segment 47 a charging circuit for the condenser 56 whereupon this condenser armature and contact thereof,

is charged. The contact 31 of the transmit ter 24 being open, the'pole changing relay 29 is caused to reverse theposition of its armature upon the passage of the brush 12 over the segment 19 to which contact 31 of the transmitter is connected. Similarly the receiving relay 37 at'office B reverses the position of its armature and consequently causes the deenergization of relay 38. Thus, upon the passage of thebrush 42 over segment 48 of the distributor G, the condenser 57 will not be charged. Contacts 32 and 34 of the transmitter 24 being closed, conditions similar to those described in connection with contact 30 will be established for causing the charging of condensers 58 and 60 in accordance with the energization of relay 38, upon the passage of the brush 42 over the segments to which these condensers are connected. Condenser 59 will however, not be charged owing to contact 33 of the transmitter 24 being open so that an open circuit condition is established upon the passage of the brush 42 over the segment individual thereto.

Just prior to the completion of the cycle of rotation of the brush arm 41, and provided relay 62- is still energized, an energizing circuit will be established for relay 63 extending from battery through the armature and contact of relay 64, winding of relay 63, front contact of relay 62, segment brush 42 and segment 46 of the distributor G to ground. Relay 63 is thereupon energized and locked up which establishes at its left hand contact a short circuit for the condenser 67, otherwise, no effeet is produced due to the energization of this relay.

If relay 62 is deenergized at the time brush 42 crosses segments 46 and 52 then relay 64 will be energized instead of relay 63. Relay 64 will open the locking circuit of relay 63 releasing it if it had been previously energized.

The brush 88 of the multiplex distributor I in passing over segment 96 completes an energizing circuit for'relay 65 extending from battery through ring 98, brush 88, segment 96 of the distributor I, contact 69 on the relay 66 and the winding of relay 65 to ground. Relay 65 in closing'its left hand contact opens the locking circuit of the relays 76 to 80 inclusive thereby restoring any one of these relays which have previously been energized to normal and also establishes an auxiliary locking circuit for relay 62 for preventing the release of this relay and relays 70, 71 and 72. Upon the closure of the right hand contact of relay 65 an energizing circuit for relay 66 is established extending from battery through the ring 98, brush 88, segment 96, right hand contact and armature of relay 65 and the winding of relay 66 to ground. Relay 66 in energizing locks itself up through its left hand contact and remains locked up until brush 88 passes off of segment 96. Belay 66 opens the original energizing circuit of relay which thereupon releases its armature and again conditions the locking circuit of the storing relays 76 to inclusive, while at the right hand armature or relay 66 and at the left hand armature of relay 65 the locking circuit of relay 62 is broken thereby causing the deenergization of this relay and consequently the deenergization of transfer relays 70, 71 and 72. Upon the release of the transfer relays 70, 71 and 7 2, a discharge circuit is established for the condensers 56,

58 and 60 through the armatures and contacts of the transfer relays 70, 71 and 72 to the right hand winding of the storing relays 76, 7S and 80. These relays will be thus energized and locked up over acircuit from battery through the left hand armature and winding thereof and the left hand normal contact of relay 65 to ground. Inasmuch as the condensers 57 and 59 for the particular selection chosen were not charged no result will be produced on the relays 77 and 7 9 corresponding to these condensers, upon the deenergization of the transfer relays 70, 71 and 72. When brush 88 passes off of segment 96, relay 66 is released thus preparing the locking circuit for relay 62 so that relays 70, 71 and 72 will be energized upon the subsequent operation of relay 62 during the next cycle of revolution.

If the multiplex brush 88 passes over segment 96 so as to deenergize relays 70, 71 and 72 before the start-stop brush 42 has passed over segment 51, one or more of the storing relays may be operated directly by an impulse from the corresponding receiving segment. In such cases, the corresponding condenser serves only to slightly prolong the current impulse through the storing relay.

Nhen the phase relations between the brush arms 41 and 87 of the start-stop distributor G and multiplex distributor I respectively is such that brush 88 is passing over segment 96 at the time that relay 61 is energized by a starting impulse as previously described, relay 62 will be energized, but it will not be locked up unless relay 66 releases to establish a locking circuit before the cessation of the brief impulse through its left hand winding allows relay 62 to release and open the locking circuit at its right hand contact. If relay 62 fails to lock up, relays 70, 71 and 72 will not be energized and the signal selection will be transferred directly from the start-stop distributor segments to the storing relays. If during the succeeding revolution, the multiplex brush arm 87, which runs at a slightly higher average speed than brush arm 41, has gained sumciently so that relay 66 can release in time to lock up relay 62, relays 70, 71 and 72 will be energized and the signal selection will be stored on the condensers to be transferred later to the storing relays in the manner previously described. In such a case, relay 62 will remain operated for nearly a complete revolution of the brush arms with the result that relay 63 will be energized and locked when brush 42 crosses segments 46 and 52. The left hand armature and contact of relay 68 will short circuit condenser 67 thus prolonging the next operating impulse through the left hand winding of relay remain operated until its locking circuit is established at the right hand contact of relay 66.

When the multiplex brush arm 87 has advanced in phase relative to the start-stop brush arm 41 to an extent such that relay 62 is released when brush 42 crosses segments 46 and 52 an energizing circuit is established for relay 64 which as previously described controls the locking circuit of relay 6?). The energizing circuit for relay 64 extends from battery through the winding thereof, left hand normal contact and armature of relay 62, segment 52, brush 42 and segment 46 of the distributor G to ground. Relay 64 in energizing merely opens the locking circuit for relay 63 which is then re stored to normal for removing the short circuit from about the condenser 67. Thus, upon the engagement of the brush 42 with the segments 53 and 54 conditions similar to that described for the initial operation of the system will be brought about, that is, the condenser 67 will be charged and a momentary surge of current through the winding of the relay 62 produced for causing the energization and locking of'this relay.

Upon the passage of the brush 89 of the multiplex distributor I over the respective ones of the segments to which the relays 76 to 80 inclusive are connected, a polarity of battery depending upon the energization of the storing relays 7 6 to 80 will be applied to the apex of the ratio arms to which receiving relay 99 is connected and thence over the line conductor 7 to the central oliice C. The brush 89 in passing over segment 94 to which the armature of storing relay 76 is connected impresses on the line conductor 7 an impulse of a positive polarity which passes through the windings of the receiving relay 101, for causing the reversal of its armature. The negative pole of the battery associated with the contacts of this relay is thereupon connected with the continuous ring 113 of the distributor M so that upon the passage of the brush 104 over the segment to which the storing relay 115 is con nected, this rel-a will be energized over a circuit extending from battery, upper con tact and armature of relay 101, ring 113,

62 to insure that it willv brush 1041., segment 107 and the winding of relay 115 to ground. This relay in attract ing its upper armature establishes a locking circuit therefor extending from battery, through the winding of relay 127, upper armature and contact of loop contro relay 122, upper armature and contact of relay 115 and, the winding thereof to ground. This relay 115 will thus remain energized until the locking circuit is broken at the contact of the loop control relay 122. Relay 127 which conditions an energizing circuit for the release magnet 131 of the start-stop distributor R is also energized over the circuit just traced. It may also be noted at this point that relay 127 is energized upon the energization of any one of the storing relays 115 to 119 inclusive. As the brush arm 87 continues to rotate, conditions depending upon the position of the armatures of the storing relays 76 to 80 inclusive will be set up for causing the corresponding positioning of the armature of receiving relay 1.01 at the central OfllCB C. Thus, upon the passage of the brush 101 over the segments to which the storing relays 11 6, 117, 118 and .119 are connected these relays will be energized depending upon the energization of the storing relays 76 to 80 at the central ofiice B. F or the particular selection chosen storing relays 117 and 119 will be energized over circuit s similar to that traced in connection with storing relay 115. The energized ones of these storing relays will be locked up tl'irough their contacts in a manner similar to that described in connection with storing relay 115. Upon the pas sage of the brush 101 over the segments to which storing relays 116 and 118 are'coir, nected these relays will not be energized owing to the position of the armature of relay 101.

Following the passage of the brush 89 over segment 90 of the multiplex distributor I, the brush 88 engages segment 96, whereupon an energizing circuit is established for relay in the manner previously described which in turn causes the energization of relay 66 and the opening of the locking circuit of the storing relays 76 to 80 inclusive which had been previously. energized. Similarly, relay 65. releasing while relay 66 is operated causes the deenergization of the transfer re lays 70, 71 and 72 for transferring the im pulses stored in the condensers 56 to 60 in accordance with the next selection to the storing relays 7 6 to 80.

Following the passage of the brush 101 of the multiplex distributor M over segment 111, brush 103 engages segment 112, whereupon an energizing circuit is established for the release magnet 131 of the start stopdistributor It. This circuit extends from bat tery, through the winding of release magnet 131, contact and. armature 01" control relay 127, segment 112, brush 103 and the continuous ring 11a to ground. Release magnet 131 upon being energized withdraws its release latch from engagement with the brush arm 128 thereby permitting the rotation thereof. The brush 130 carried by the brush arm 128 consecutively connects the segments 132, 133, 134;, 135 and 136 which are connected with respective windings of the loop control relays 122 to 126 inclusive and the lower armatures of the storing relays 115 to 119 in circuit with the winding of the pole changing relay 142. Thus, upon the passage of the brush 130 over the segments to which the winding of the loop control relays 122 to 126. are connected, these relays will be energized and locked up for a period equal to the length of the segments to which they are connected provided the corresponding storing relays are energized. gagement of the brush 130 with the segment 132 and upon the passage of the brush off of segment 137. pol changing relay 142 is de energized thereby impressing upon the extension circuit 8 an impulse of a positive polarity which upon being received at the branch office 1) causes the reversal of the armature of the receiving relay 146. Relay M6 in reversing the position of its armature causes the deenergization of relay 151 which in turn closes through its back contact, an nergizing circuit for the release magnet 150 of the receivii'ig distributor, thus releasing brush arm 147 for rotation.

Upon the passage of the brush 130 over segment 132 and since storing relay 115 is energized, an energizing circuit is established for relay 122 extending from battery through ring 138, brush 130, segment 132 of thedistributor R, winding of relay 122, lower armature and contact of relay 115 and the winding of pole changing relay 1&2 to ground. A locking circuit for relay 122 is established upon the closure of its lower contact to thereby insure the closure of the loop including the winding of the pole changing relay .142 after relay 115 has released its armature due to the opening of the locking circuit therefor. Th closure of the circuit just traced causes the energization of the pole changing relay 1 12 which impresses on the extension circuit 8 an im pulse of a negative polarity. for causing the reversal of the position of the armature of receiving relay 1 16 to .the position shown in th drawing, consequently, causing the encrgization of relay 151. Relay 151 being new energized upon thepassage ofv the brush 148 over segment 161 selecting magnet 156 connected to this segment will be energized over a. circuit extending from battery through the vinding of this magnet. segment 161, brush 148. ring 154: and the alternate contact and armature of relay 151 to ground. The movement of the selecting bar under the con- Prior to en-.

trol of this magnet will be effected at this time.

The brush 180 in passing over segment 133 and inasmuch as storing relay 116 is not energized, the loop control relay 123 Will thus not be energized for closing the loop circuit including the winding of the pole changing relay 1522 which thereupon reverses the position of its armature and im presses on the extension circuit 8 an impulse of a positive polarity. Similarly, upon the passage of the brush 1&8 over segment 162 to which the selecting magnet 157 is connected, an open circuit condition is established, owing to the fact that the receiving relay 1 1-6 has reversed the position of its armature and in turn caused the deenergization of relay 151. Conditions similar to those just described tor selecting magnet 156 will be established upon the passage of the brush 148 over segments 163 and. 165 respectively for causing the energization of the corresponding selecting magnets 158 and 160 oi? the receiving printer 155. However, since the storing relay 118 is not energized tor this selection no effect will be produced on the selecting magnet 159 due to the passage of the brush 148 over segment 16st to which this selecting magnet is connected.

Upon the passage of the brush 103 off of segment 112, the energizing circuit for the releas magnet 131 is broken thereby causing the deenergization of this magnet and the restoration of its release latch to normal for causing the stoppage of the brush arm 128, atter it has completed one cycle of rotation.

Following the passage of the brush 1 18 otl of segment 165 and the passage thereof over segments 166 and 167, a circuit is completed extending from battery through the winding of printing magnet 168, segment 167 brush M8 and segment 166 to ground. Thus, the signals transmitted from the branch otfice A will be recorded on the receiving printer 155 at the branch oflice D over one channel of the line conductor 7 equipped for duplex operation.

Although the invention has been illustrated in connection with a system wherein code combinations of message impulses originating at a branch otfice are transferred to a main or central office at which synchronous printing telegraph apparatus is located and thence over a conductor equipped for duplex operation to a second central or main station having equipments similar to that just referred to from which it is transierrech over an extension circuit to a distant office, it is, of course, obvious that the invention may be readily applied to other types of systems without departing from the spirit and scope oi the invention.

\Vhat is claimed is: v

1. In combination, a main line, extension circuitsassociated with said main line, distributing apparatus intermediate the extension circuits and the main line, means comprising a series of electrostati means and electromagnetic devices for providing a complete overlap between the selections received from the extension circuits and those transmitted over the main line, and means for providing an overlap between the selections received. from the main line and those distributed to the extension circuit.

2. In combination, a main line, extension circuits associated with said main line, distributing apparatus intermediate the extension circuits and the main line, means for providing a complete overlap between the selections received from the extension circuits and those transn' itted over the main line, and. a set of relays responsive to impulses received trom the main line, and a like number of control relays operated in acnice with the operation of said storing relays for completing circuits from said storinq' relays to s id distributing apparatus, said relays providing an overlap between the selections received from the main line and those distributed to the extension circuits.

3, in combinatiom a plurality of central s ions connected by a line conductor, synchronous multiplex apparatus located at said central stations and connected to said line conductor, a plurality of branch offices interconnected with said central stations by extension circuits intermittently operable apparatus associated with said extension circuits and located. at said central stations means con'iprising a series of electrostatic means and electromagnetic devices intermediate said synchronous multiplex apparatus mediate the synchronous multiplex appa-' ratus and the intermittently operable apparatus for providing an overlap between the selections received from the main line and those distributed to the extension circuits.

4. in a printing telegraph system, a plurality of central stations connected by a line conductor. synchronous: multiplex apparatus located a said central stations and connected to said line conducton a plurality of branch offices interconnected with said cen tral stations by extension circuits, intermittently operable distributing mecl'ianism associated with the extension circuits and located at the central stations means intermediate the intermittently operable distributing mechanism and the multiplex apparatus comprising a series of condensers and a group of storing relays for providing a complete overlap bet-ween the selections received from the intermittently operable distributing mechanism and those transmitted by the multiplex apparatus, and means intermediate the multiplex apparatus and the intermittently operable distributing mechanism located at the other station consisting of a set of relays in combination with a group of control relays for providing an overlap between the selections received by the multiplex apparatus and those transmitted to the extension circuit through the instrumentalities of the intermittently operable distributing mechanism.

5. In combination, a plurality of central stations connected by a line conductor, synchronous multiplex apparatus located at said central stations and connected to said line conductor, a plurality of branch offices interconnected with said central stations by extension circuits, intermittently operable distributing mechanism associated with said extension circuits and located at the central stations, means at each of the central stations connected intermediate the intermittently operable distributing mechanism and the multiplex apparatus comprising a group of condensers and relays for providing a complete overlap between the selections received on the intermittently operable distributing mechanism and those transmitted by the multiplex apparatus, and a series of relays and a group of control relays at the other station for providing an overlap between the selections received on the mul plex apparatus and those transmitted to the extension circuits due to the operation of the intermittently operable distributing mechanism.

6. In combination, a line conductor, synchronous multiplex apparatus connected thereto, an extension circuit, intermittently operable apparatus connected to said extension circuit, and means comprising a set of condensers and a group of relays for providing a complete overlap between the selections received from the intermittently operable apparatus and those transmitted by the multiplex apparatus.

7. I11 combination, a line conductor, synchronous multiplex apparatus connected thereto, an extension circuit, intermittent operable apparatus connected to said extension circuit, means comprising a group of electrostatic means, and a set of relays for providing a complete overlap between the select-ions received from the intermittently operable apparatus and those transmitted by the multiplex apparatus 8. In combination, a main line, synchronous multiplex apparatus connected thereto, intermittently operable distributing mechanism associated with said multiplex apparatus. means comprising a group of condensers and a set of relays for providing a complete overlap between the selections received on the intermittently operable distributing mechanism and those transmitted by the multiplex apparatus, and means controlled jointly by the intermittently operable distributing mechanism and the multiplex ap paratus for transferring the eitects of said electrostatic means to said relays,

9. In combination, a main line, a synchronous multiplex apparatus connected thereto, intermittently operable distributing mechanism associated with said multiplex apparatus, means comprising a group of condensers and a single set of relays for providing a complete overlap between the se lections received on the intermittently operable distributing mechanism and those. transmitted by the multiplex apparatus, and a group of relayscontrolled by said multiplex apparatus for establishing a discharge circuit for said condensers to said set ot storing relays whereby said relays are energized in accordance with the condensers which have previously been charged.

10. In combination, a line conductor, synchronous multiplex apparatus connected thereto, an extension circuit, start stop distributing apparatus associated with said extension circuit, means intermediate said multiplex apparatus, and said start stop distributor comprising a set of storing relays and set of control relays controlled jointly by said storing relays and said start stop distributor, for providing an overlap be tween the selections received on the multiplex apparatus and those transmitted by the start stop distributing mechanism.

11. In combination, aline conductor, synchronous multiplex apparatus connected thereto, an extension circuit, a start-stop distributor associated with said extension circuit, means intermediate said multiplex apparatus and said start-stop distributor com prising a group of relays and a set of control relays for providing an overlap between the selections received on said multiplex ap paratus and those transmitted by said startstop distributor, and means operated upon the energizatioin of any one of said storing relays for conditioning the release of said start-stop distributor.

12. In combination, a line conductor, synchronous multiplex apparatus connected thereto, an extension circuit, start-stop distributing mechanism associated with said extension circuit, means intern'iediate said multiplex apparatus and said start-stop dis tributing mechanism comprising a set of storing relays, and a group of loop control relays controlled jointly by said start-stop distributing mechanism and said storing relays for providing an overlap between the selections received on the multiplex apparatus and those transmitted by said start-stop distributing mechanism.

13. In combination a line conductor, an extension circuit, signal storing means intermediate the line conductor and the extension circuit comprising a plurality of electro- 5 magnetic devices for providing an overlap between the selections received from said line and those transmitted to the extension circuit, and means for efiecting the release of said electromagnetic devices sequentially.

In testimony whereof, I have signed my 1 name to this specification this 11th day of January, 1922.

GILBERT S. VERNAM. 

